I have a 1997 Civic DX HB, no modifications, completely stock, that will start fine the first time during the day. After I drive it a while and turn it off it will just crank and not start. I have to wait usually about 30-60 min before it starts again. I do not smell gas when it is cranking (I know it only pumps gas for a few seconds). This has been going on for about 3 years and I have not been able to solve it yet. I have went through and tested everything I could find on every Honda forum and have not been able to solve it. Just off the top of my head here are some things I have tried: 7 main relays (new, re soldiered, and junk yard pulls), 3 computers, fuel pump is priming (also tested voltage), replaced fuel filter, correct fuel pressure on valve at filter, tested spark (good), cleaned and sanded all contacts on battery and grounds on car, tested ohms/voltage? at injectors, I have tried/tested all of these things and switched out parts that were possible to switch out while problem was present. Also swapped out 2 fuel pressure regulators (with junk yard pulls), changed internals in dizzy, checked all fuses under dash and in engine. I'm sure I have forgotten a few things but I just wanted to let you know what I have done (as I said as much as I can remember at this time). Car had a major tune up about 2 years ago and only has about 400 miles on it since then. The only problem that has caused a CEL is "P0118 Engine Coolant Temperature Sensor 1 Circuit High Voltage" which seems to happen about every 4-6 months and I change it. Other than that the car runs great! Any suggestions would be appreciated, I've spent very many hours troubleshooting and don't want to have to pay a mechanic. Thanks!

 

When it doesn't start is it not getting spark or fuel or both?

 

Yes, it is getting both when problem is present. Tested for spark (all plugs) and fuel pressure.

 

You say there is fuel pressure but are the injectors spraying

 

I tested the ohm resistance in each injector both when the car was running normal and when it wouldn't start. Both are identical and within range.

 

This^ is almost surely the cause of the hard starting problem.

 

I think you could possibly be right. the CEL PO118 only comes on every several months, then I change the sensor (free under lifetime warranty). But even during the months there is no CEL the starting problem is still there. The car is completely stock. None of the wiring leading from that sensor have been touched and everything seems to be in place. If you have any further suggestions on how to test from the sensor down, I'd appreciate it. (By the way, I'm not an electrician, but have a little experience with wiring).

 

You've replaced the ECT sensor multiple times. The time to test the two wires is long past due. If they're good, then the ECU is bad.

 

I've replaced the ECU already with two other known working ones while the problem was happening. I guess it might be in the wiring somewhere, but that is absolutely my worst area. Any ideas, suggestions, or easily followed diagrams on how to trace and test them?
Thanks much!

 

Test the two ECT sensor wires - one for voltage (5V) and the other for a short or open.

Click the FAQs sticky to learn about basic electrical tests.

 

You might have to take a look at the circuit and start tracing wires to see whats going on.

 

So I finally got around to testing the sensor wires for voltage (Christmas and rain kept me from doing so). I did a base test on my battery and got 12.44v. I then connected them to the sensor plug and got two different readings. When connecting them one way I got a reading of 11.96v and then reversed the leads and got a fluctuating voltage around 12.11 volts. I know this is bad and must have a short or open circuit but I'm no electrician so any detailed advice and directions would be greatly appreciated. On a side not the Haynes manual says the wire from the sensor to the PCM is red/white, mine is green/black. Thanks for any/all help!




Haynes says wires should be red/white, mine are green/black.....

 

i think that's the radiator fan switch. the sensor you want is under the distributor in the head. one should read 5v with the red multimeter lead on it and the blk lead to body ground.

 

make sure you dont have coolant wicking up the wiring and check the crank sensor when the issue occurs